1. Field of the Invention
The present invention generally involves the field of technology relating to self-leveling support devices for heavy machinery and appliances. More specifically, the invention pertains to an improved self-leveling assembly for domestic appliances, and particularly for the rear pair of corner support legs of an automatic washing machine disposed on an uneven support surface.
2. Description of the Prior Art
It is known to provide devices and assemblies for realizing the self-leveling of a heavy piece of machinery or appliance so that uneven weight loading can be redistributed on an uneven support surface This is particularly important in certain machines and appliances which produce strong vibrations and therefore require stable and level support during their operation.
A domestic automatic washing machine, for example, is often installed on a basement or utility room floor that is intentionally sloped to provide for proper drainage. Since the machine requires support at each of the four corners of its base, it is necessary to adjust the length of each leg at each corner in order to accommodate the unevenness of the support surface and dispose the machine in a level and stable position for proper operation. This is especially important during the spin cycle of the machine wherein strong vibrating forces are quite high and will cause the machine to shake or move if it is not properly and evenly supported at its four corners.
A washing machine is typically installed with its rear portion adjacent a back wall, and often with other appliances, such as a dryer, and possibly a side wall positioned adjacent the side portions of the machine. Such an installation does not interfere with adjustment of the front two legs of the machine since these legs are easily accessible and leveled through simple screw adjustments. However, because the rear portion of the machine is inaccessible after installation, a self-leveling means must be provided to permit automatic adjustment of the two rear legs.
Conventional self-leveling devices and assemblies for washing machines generally involve interconnecting the two rear legs together by a center bar section to create a rigid unit which is then secured to the machine frame by means of stationary brackets provided with angled slots in the walls thereof, with pins carried by the legs being disposed in sliding engagement through the slots. The self-leveling function is realized through the interconnection of the rear legs by the center bar section so that as one leg is retracted, the other leg is automatically extended. When the machine is disposed on a support surface that slopes downwardly toward one side or the other of the machine, the rear legs will remain in contact with the floor and support of the machine at both rear corners is established by the pins being engaged against the edges of the slots under static friction.
Because of the rigid connection of the center section and the two rear legs, adjustment requires tilting of the center section from the horizontal in a direction corresponding to the retraction and extension of each leg, so that the entire supporting force is sustained at the frictional engagement points defined by the pins and edges of the slots. An arrangement of this type is disadvantageous in that tilting of the center bar section necessarily results in corresponding tilting of the legs from the vertical because of the rigid connection therebetween. If the unevenness in the support surface is minimum and the degree of self-leveling adjustment is low, the tilting of the legs from their respective vertical orientations may not be sufficiently pronounced to affect stability of their support function. However, if the degree of adjustment is high, then it is apparent that the more extended leg will experience pronounced tilting which could adversely affect the stability of the machine during its operation.